Questions tagged [antenna]

Questions about the design, selection, building, testing, mounting, or properties of antennas. See also specific tags: [antenna-theory], [antenna-construction], [dipole], etc.

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3answers
342 views

Tweak antenna resonant frequency higher

This is a very simple question and I'm sure if I had a bit more background knowledge, I could figure it out myself. Let's say I have a 1/4 wave vertical antenna that is slightly too long, but it is ...
2
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2answers
251 views

Beamwidth of omni-directional antenna with gain

I am looking to buy a wifi antenna for a boat to connect to shore based wireless hotspots that may be "far" away. Due to the waves, I am assuming that the antenna mast sways +-15° from vertical. The ...
2
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2answers
96 views

Low mass, low frequency transmission line

I'm interested in a low frequency (10 MHz - 100 MHz) radio receiver array, made up of crossed dipole antennas. I'm working on a design project mainly focused on the mechanical engineering side of ...
2
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1answer
839 views

How can the gain of an antenna be negative?

Aaronia released this ultra-wide-range antenna, that can measure up to 35GHz. This was really impressive for only 3000 Euros, so I was considering purchasing it, when I figured I would look at the ...
2
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1answer
87 views

Can an indoor antenna damage unshielded electronics?

I have a 25w radio running through a ~4.5db gain antenna. If I use a 4W HT indoors, I can hear a loud buzzing noise emmanating from my computer speakers. If I used the 25w mobile with the 4.5db gain ...
2
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2answers
492 views

G5RV Jr. fed with ladder line and coax

I am a new ham and I was just given a G5RV Jr. I have about 20 feet of coax plus about 60 feet of 450 ohm ladder line I can feed it with. Can I extend the G5RV Jr. feed line with the ladder line I ...
2
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2answers
159 views

Is a “shorted” coax feedline ok for a G5RV type antenna?

I have "inherited" what I believe to be a G5RV antenna with two 51 foot wire centerfed radiators. If I remember correctly from measuring 2 months ago, there is about 31 feet of 450 ohm ladderline ...
2
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3answers
167 views

Can the tip of an antenna burn insulation/drywall?

In my house, I’ve got a mag mount antenna mounted on a piece of sheet metal on top of rubber and the tip of the antenna goes into my ceiling and possibly contacts or is near to home insulation. I was ...
2
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4answers
1k views

Can I install a Diamond X30A Antenna on a Balcony with a Metal Rail?

I live in an apartment with a metal rail patio very similar to the attached photo. I want to put a Diamond X30A on the patio but the radials will be about a foot below the top rail. Will this work, or ...
2
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2answers
253 views

Reciprocity for loopstick antennas?

What is the reason a small loop-stick antenna ( typically used for AM reception) does not have reciprocal characteristics for both reception and transmission. ( AM reception works great on those ...
2
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1answer
243 views

Influence of bending and asymetric ground wire on monopole antenna

I'm currently building a rc radio system using the 433mhz RFM69W transceiver, so far everything works fine, but i am not sure about the way i laid out my antenna and how the layout cripples the ...
2
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3answers
718 views

Would a 2.4ghz yagi antenna work for Ham Radio?

I am building a miniature yagi antenna that is made for 2.4ghz. Would a 2.4ghz yagi antenna work for Ham Radio?
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1answer
1k views

Why does a counterpoise need to be grounded

I made a 1090Mhz antenna for ADS-B following the instructions from sprut.de. The antenna looks like below and I made it from the copper centre of some stripped coax: The instructions say: Now we ...
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4answers
1k views

will my G5RV Jr. work/tune beside the house

My house is vinyl sided with aluminum around the windows. But will the inverted vee tune? will it adversly effect the radiation pattern of the G5RV ?
2
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3answers
1k views

Airband Jammed on Yaesu VX-6R

I am an owner of a Yaesu VX-6R. This radio works great on amateur bands. As a glider pilot I often need to hear the frequency of the local airport. I would like to find out whether this radio is ...
2
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2answers
392 views

Horizontal dipole for a 80 foot span?

I have the K1JEK Cobra UltraLite and it works exceptionally well. However that was when I had a larger yard. Moved to a house with a smaller lot and now can't use the JEK Cobra (max span between trees ...
2
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1answer
1k views

What antenna to use for medium frequencies in an apartment building?

I'm living at the 6th's and top floor of an apartment building. I have a balcony with a metal balustrade. Above the balcony there is a metal roof rail. I need an antenna which won't be noticed by the ...
2
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1answer
134 views

Why do some 1/2 wave collinear designs have a 1/4 wave element?

I think I understand the basic principles of a collinear antenna. How the Coaxial Collinear Antenna Works? seems to describe it well. However, I've just repaired a 1090MHz (ADS-B receive only) ...
2
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2answers
177 views

resonance vs resonator in antenna

Resonance in electronic means: reactance of zero. (maybe wrongly/correctly someone's calling the minimum VSWR, the resonance of antenna! and this cause confusion) I've heard in Antenna Design for ...
2
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4answers
722 views

What is the maximum and minimum of antenna gap of dipole antenna?

Consider the picture below is design of half wave length (λ) dipole antenna. I read some explanations saying that it is the best design to get the optimum transmit power. Half wave length (λ) is from ...
2
votes
1answer
196 views

Yagi-Uda antenna - energy flow density calculation

This task is our milestone, even the lecturer doesn't know how to do it, I will be grateful for even the smallest clue, thank you in advance. There are given two, identical, parallel, short dipoles ...
2
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1answer
120 views

What type of this antenna is it?

Could you please tell me which kind of this antenna is? I supposed it is a modified dipole, but not quite sure. Is there any available equation for calculating the original dimensions of this type of ...
2
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3answers
3k views

Feeding a dual-band UHF and VHF Yagi antenna

I just built a UHF Yagi antenna for my HT, and I was thinking about adding VHF elements. If I do, could I just connect the coax directly to both sets of elements without a diplexer?
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2answers
3k views

best antenna for Baofeng

My wife is a teacher at a school about 15 miles from our home. My growing concern about a possible EMP event (natural or man-made) led me to buy a pair of Baofeng UV-5RV2+ radios in the hopes of ...
2
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2answers
695 views

How to tune a hamwhip-type mobile HF antenna?

I'm a new ham and would like to start working HF with my mobile (my only) rig, an FT-857d. I have a handful of antennas, all of the variety that has a fiberglass base, extended by a stainless steel ...
2
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1answer
1k views

How do I specify that wires are connected in 4NEC2?

I've been trying to get acquainted with the 4NEC2 antenna modeling program. Perhaps this is obvious, but it's not clear to me that wires with one end in the same place are connected. I'm attempting ...
2
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8answers
2k views

What kind of 2 meter antenna is this?

At first glance this appears to be a simple ground plane but there is far more going on. The ham who built this back in the '80s is now SK and I can't find anything else like this anywhere. The ...
2
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1answer
744 views

What material is best to design a dipole antenna working at VHF frequency? [duplicate]

I need to design an antenna using the tool FEKO. The antenna is supposed to work in VHF frequency and has a gain of around 2.2 dB. What is the best material to use and what are the specifications of ...
2
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3answers
556 views

Maximum Thickness for NMO Mounting Surface?

How thick can the metal be for a common NMO antenna mount? I know they're meant for sheet metal but can they go as thick as 1/4"? Edited to add: By "common", I mean NOT the ones designed for extra ...
2
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1answer
124 views

Portable radio antenna measurement

Just purchased a HP 8711A and have "upgraded" the bootrom to enable vector measurements. I am now trying to learn more about how to make better measurements and understand what's going on. One of the ...
2
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5answers
549 views

Yaesu FT-950 with G5RV lite antenna auto tune problem on 21Mhz

I am unable to autotune on 21Mhz as the SWR is more than 1:3 which is out side the range of the radio. I would like use it only for digital TX with a max. power of 50 watts. Any solution/s?
2
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1answer
833 views

What are the dos and don'ts when it comes to retractable antennae for HTs?

I was thinking of getting a retractable antenna for my Baofeng UV-82 8W HT. I found a Nagoya NA771R. What are the dos and don'ts for using such a retractable antenna with a HT? Should it always be ...
2
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2answers
396 views

Replace directional antenna by fixed antenna

Given the following specs of a directional antenna: ...
2
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1answer
303 views

Should I ground a 2 array crossed yagi-uda antenna?

I am using 2 array crossed yagi-uda antenna operating at 437.025 MHz. Where and how should I ground it? Should I ground at mast of antenna or to its metallic boom?
2
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1answer
1k views

What are the effects on an ATAS-120A screwdriver antenna with a limited ground plane?

I'm going to be installing an ATAS-120A screwdriver antenna at the corner of a metal roof building, without radials going out over 270 degrees of the plane it's on. Will this significantly change the ...
2
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1answer
254 views

Maximum Input Wattage of MFJ-1717PL Antenna

I was wondering if anybody knew the maximum input wattage of the MFJ-1717PL Antenna. I was going to use this with the Yaesu FT-1900R mobile radio mounted in a Pelican case.
2
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2answers
251 views

Can I use two antennas and coax to couple RF into my aluminum sided house?

I have an aluminum sided house, and when I'm using my HT I typically need to be near a window for it to work well. Would I gain much if I put an antenna on the roof, an antenna in the middle of my ...
2
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1answer
43 views

Total radiation pattern in antenna arrays

let's consider a simple linear uniform spaced array: We know that, from elementary array theory, the total pattern (for instance in terms of E-field) may be evaluated, in case no phase shift is ...
2
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1answer
42 views

Cobra hand held 50wxst aftermarket antenna

I’d like to add an aftermarket antenna to my cobra HH50wxst to boost my range. My only concern is if I got a longer antenna, could it possibly throw off the SWR and damage the radio? I am totally new ...
2
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1answer
92 views

Anyone know what this antenna is?

Hello, what kind of antenna is this? I’ve been trying to figure it out for 14 years. None of my neighbors know. Whomever installed it either moved or passed away.
2
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1answer
142 views

Questions about effective isotropic sensitivity(EIS)

Recently, I read something about EIS (effective isotropic sensitivity) and TIS (total isotropic sensitivity). I'm trying to understand the concept, but I find it's quite hard for me. In the book ...
2
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1answer
99 views

144/430 MHz antenna on 155 MHz?

We have a local radio shop that started selling us Relm P150s with a high gain 9 inch antenna, and those are ok. He also has thrown in longer 15 to 14 inch dual band antennas saying use those in ...
2
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1answer
85 views

Convert NEC antenna file to .out-file for Wattwächter

I've just wrote a NEC Antenna file of my longwire with xnec2c on Ubuntu. To calculate protection distance with Wattwächter, I need an .out-file. Protection distance means the safety distance for human ...
2
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1answer
570 views

300 ohm to 50 Balun at antenna feedpoint, or near receiver?

If I build a folded dipole, it will have an impedance close to 300 ohms. I have to match this impedance to the 50 ohms of my transceiver. I know many people match that impedance with varying lengths ...
2
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1answer
111 views

Do these magnetic field measurements of end-fed and center-fed half-wave dipoles corroborate measurements made by antenna experimenters?

Using a sensor and procedure discussed in my article, I made the following plot comparing the magnetic field strength along a 30m-band half-wave dipole fed at center and one end. Key points include: ...
2
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1answer
99 views

Radio antenna for my FM receiver / Android FM

I want to make a radio antenna at home which will be able to receive all FM frequencies for my FM radio or Android FM. How do I make it? Frequency it can catch : 88 - 108 MHz Thanks.
2
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1answer
76 views

SWR characteristic changes when lifting coax off the ground?

I was at Anaheim HRO and few guys there were talking about an MFJ all band vertical antenna that does not need radials. I forget what model number it is but it is one of those "wife pleasing antennae" ...
2
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2answers
745 views

Bow Tie antennas impedance

I see on the internet that a radio amateur made bowtie antennas for transmitting and receiving on the 2 meter and 10 meter bands. They produced very good SWR bandwidth when fed with 50-$\Omega$ coax. ...
2
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1answer
44 views

Triband vertical antenna 6/2/70

I wish to fit this on the house gable end, however the location has a metal phone line bracket that will be just bellow the antenna radials. Will this cause any detrimental effects?
2
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1answer
171 views

Is it possible to make antenna for one specific frequency?

I have a GSM Modem that works on 2300MHz Frequency (LTE), but it could only receive 3 bar of signal strength. I plan to make a DIY directional antenna that is made specifically for this Frequency ...

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